Key facts
- Length: up to 20cm
- Distribution in Scotland: Three populations: Dumfries and Galloway; Islay; and Argyll
- Status: Protected species (Wildlife and Countryside Act); IUCN – Near Threatened
- Species on the Edge areas: Argyll and Inner Hebrides
Species information
How to identify
The medicinal leech is a large leech; it can grow up to 20cm in length. In Scotland, it is dark brown with longitudinal yellow-grey stripes. In England and Wales, they are more vibrant in colour with red and yellow stripes. Its underside is pale and speckled.
Lifecycle
Medicinal Leeches are hermaphrodites and reproduce in late summer. They lay spongy cocoons below stones on the shore or amongst plant roots just above the water. They take at least two years to reach breeding maturity, but this may take as long as four years.
Distribution
The medicinal leech is found in three locations in Scotland: Islay; near Oban; and in Dumfries and Galloway.
There are around 20 isolated populations in the UK; from Kent, Hampshire and Cumbria in England, Powys, Glamorgan and Anglesey in Wales, and Argyll, Dumfries and Galloway and Islay in Scotland. It is now considered extinct in Ireland.
Habitat and feeding
Habitat: Shallow freshwater pools with muddy bottoms, fringed with reeds and some hard/rocky edges. It must have access to deer/livestock for feeding and vegetation control.
Feeding: Blood from mammals, amphibians, fish and birds
Conservation status
- Protected species (Wildlife and Countryside Act)
- IUCN – Near Threatened
Threats
- Loss of wetland habitat
- Changes to grazing regimes
- Use of livestock worming treatments
What Species on the Edge is doing
- Conservation breeding programme
- Habitat improvement
- Engagement with local communities to increase awareness and encourage people to look out for them
Our work for the medicinal leech
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